Personally I abhor the idea of a plugin downloading components from outside. I mean, your plugin on the repo should have everything you need. If you need to fork, you make your own plugin folder because you can prevent it from being overwritten.

The idea is just to seperate each download with multiple buttons from the plugin page.

And if a mendatory part of the plugin is not active (for the download core in administration), it is not possible to activated the SUB parts or an automatic installation/activation of mendatory SUP part start automatically...